The present invention pertains to a device for removing a screw or pin tightly seated in a mounting hole of a bearing eye or the like, especially a tightening screw or fastening screw of a pivot pin or the axle component of a motor vehicle axle, with a support body having a lateral support wall, with which support wall the support body can be attached to the bearing eye in the area of the screw, wherein the support body is provided with a pressing device acting on the screw.
Motor vehicle axles in which essentially cylindrical pivot pins are held clampingly in a bearing bore of a slotted bearing eye have been known. The pivot pin is part of a ball-and-socket joint, which is arranged, e.g., at the outer end of a suspension arm of a motor vehicle axle. The bearing eye with its bearing bore for receiving the pivot pin may be arranged, e.g., at the upper end of a steering knuckle of the motor vehicle axle. To hold the pivot pin tightly in the bearing bore, the bearing eye has a clamping slot, which extends radially in relation to the bearing eye in the area of the bearing bore and by which two clamping flanges are formed, which are provided with a corresponding mounting hole for a tightening screw. In cooperation with a tensioning nut which can be screwed onto the tightening screw, the bearing bore can be tensioned by the tightening screw. The pivot pin is tensioned in a tightly seated manner in the bearing bore by this clamping operation. To also ensure that the pivot pin cannot slip out of the bearing bore even when the tightening screw is loosened but not removed, this tightening screw is arranged, extending at right angles to the bearing bore, at a radially spaced location from the bearing bore, at which the tightening screw laterally protrudes at least partially into the bearing bore. The pivot pin correspondingly has a circular mounting groove, into which the tightening screw protrudes in the mounted state. Thus, there is a positive-locking connection between the tightening screw and the pivot pin via the circular mounting groove of the pivot pin, so that the pivot pin cannot slip out of the bearing bore of the slotted bearing eye even when the tightening screw is loose.
It has been found with this type of joint connections that the tightening screw rusts into its mounting holes after a prolonged operating time and thus can be removed only with difficulty. It is sometimes necessary to heat the bearing eye in order to be able to move the tightening screw in the mounting holes at all. However, the ball-and-socket joints, which are provided with rubber cuffs toward the bearing eye, are very greatly affected by this heating of the bearing eye. The consequence of this is in turn that during simple repair work, during which the ball-and-socket joints are actually not to be replaced, these ball-and-socket joints are damaged and must be additionally replaced, as a result of which the repair costs increase considerably. However, since the tightening screw partially protrudes into the bearing bores of the pivot pins, complete removal of the tightening screw is absolutely necessary for the removal of the pivot pins from their bearing bores.
For example, a device which is intended especially for pressing out pivot pins of a steering linkage of motor vehicles has been known from DE-GM 69 01 578. However, this device is suitable only for pressing out conical pivot pins which become completely loosened after a short pressing-out movement simply because of their conical design in the bearing bore of the pivot pin, which likewise has a correspondingly conical design. For support in the area of the bearing eye, this device has a support body with a support wall arranged at right angles to the longitudinal extension of the device in the form of a support fork. A threaded cylinder with internal threads, which is arranged approximately concentrically to and opposite the support fork, is provided at the other end of the support body opposite the support fork. A pressing spindle acting as a pressing device, by means of which the pivot pin can be loosened in the bearing eye with the prior-art device attached to the bearing eye, is screwed into the threaded cylinder. It was now found that this device is not suitable for pressing out an extremely tightly seated tightening screw of the above-described type because especially the part of the pressing spindle that points toward the bearing eye and presses the threaded section of the tightening screw always becomes deformed. Furthermore, great wear can also be observed on the thread of the pressing spindle if this prior-art device is frequently used to press out extremely tightly seated :pivot pins. However, the internal threads of the threaded cylinder will also be damaged by this wear over time, so that this device cannot be used any longer already after a short time.
Furthermore, motor vehicle axles in which shock absorbers are fastened to the axle body via a bearing eye have been known. The bearing eye has a mounting hole for this, through which a fastening screw is passed. The bearing eye of the shock absorber is mounted between two bearing flanges, through which the fastening screw passes as well. To securely hold the bearing eye between the bearing flanges, the fastening screw is provided with a retaining nut. It was also observed in this case of connection that the fastening screw can rust into the mounting hole of the bearing eye after a prolonged operating time of the vehicle and its removal, e.g., to replace the shock absorber, is extremely difficult. The fastening screw is frequently seated in the mounting hole so tightly that it cannot be loosened and pushed out with conventional means any longer. The above-mentioned prior-art device is also unsuitable for loosening such fastening screws, because the pressing spindle is also damaged in the case of extremely strong pressing forces.
The basic object of the present invention is therefore to provide a device by means of which extremely strong pressing forces can be applied to loosen and/or press out a screw or pin tightly seated in a mounting hole without the device being subject to increased wear.
The object is accomplished according to the present invention by the pressing device having a guide cylinder, in which a stud is guided axially displaceably in a guide hole for loosening and/or pressing out the screw and by a screw-down nut, which is screwed on the guide cylinder and is provided with a pressing surface acting on the stud, being provided for the axial displacement of the stud.
Due to the design of the device according to the present invention, extremely tightly seated screws or a pin can be reliably pressed out of a corresponding mounting hole of a bearing seat without the device itself being able to be damaged.
The pressing device has for this purpose a guide cylinder in which a stud is guided axially displaceably. To guide the stud, a guide hole is provided, which can be pushed fittingly over the threaded section of the tightening screw or fastening screw projecting from the bearing eye with the stud withdrawn. To apply the necessary strong pressing-out force, a screw-down nut with a pressing surface is provided, which is screwed onto an external threaded section of the guide cylinder, which threaded section has a relatively large diameter. Due to this relatively large diameter of the threaded connection between the screw-down nut and the guide cylinder, extremely strong axial forces can be applied by the screw-down nut via its pressing surface on the stud without the threaded connection being able to be damaged. Deformations of or damage to the stud are also ruled out because the stud is securely guided in the guide hole of the guide cylinder and is protected from external effects. Furthermore, the threaded connection between the screw-down nut and the guide cylinder is designed such that the use of an impact screwdriver is possible without damage to this threaded connection. Due to this design according to the present invention, extremely tightly seated tightening screws can be reliably loosened with the pressing device according to the present invention, because an additional loosening effect is exerted on the tightening screw in its mounting hole by the impact impulses applied to the screw to be loosened by the impact screwdriver via the screw-down nut and the stud. This also applies, of course, to a pin seated in a mounting hole, e.g., a pivot pin of a ball-and-socket joint of a motor vehicle axle.
Due to a design according to an aspect of the invention, the support body has an additional, second support wall extending in parallel to the support wall in addition to its support wall. The pressing device is arranged approximately concentrically to the second support wall, opposite same in the first support wall. Extremely high stability of the support body with its two support walls is achieved due to this design.
Due to a design according to an aspect of the invention, the device according to the present invention can be used in an extremely variable manner. Due to the replaceable design of the guide cylinder, the latter can be adapted to the requirements and the particular intended use, especially in terms of its dimensions. Thus, a plurality of pressing devices may be provided, which can be replaced with one another in a simple manner depending on the intended use. To guarantee a defined attachment of the device to a bearing eye, the second support wall may have an opening, through which the tightening screw or fastening screw can be pushed during the pressing out. At the beginning of the pressing-out operation, this opening surrounds the screw head of the tightening screw or fastening screw at least partially, as a result of which the support body can be accurately positioned at the bearing eye via the screw head of the tightening screw or fastening screw. This opening could be, e.g., of a U-shaped design.
To further improve this guide function of the opening of the second support wall, this support wall is designed as a mounting hole for receiving the screw head. The support body is thus held in an accurate position at the bearing eye at least at the beginning of the pressing-out of the tightening screw or fastening screw. To guarantee the most centered action possible of the force during the pressing out or the loosening of the tightening screw or fastening screw by the pressing device, the mounting hole is arranged coaxially to the pressing device of the first support wall.
The opening of the second support wall may be part of a separate mounting cylinder, which is replaceably inserted and especially screwed into the second support wall. As a result, the device according to the present invention can be used in a variable manner, because a plurality of mounting cylinders can be provided, which also have mounting holes of different dimensions for adjustment to the size of the screw head of the screw to be loosened.
For more variable use, the guide cylinder and the mounting cylinder may be interchangeable with one another as desired and be screwed into the first or second support wall.
The guide cylinder and the mounting cylinder can be screwed into the respective support wall to the extent that the bearing eye is received approximately fittingly between the guide cylinder and the mounting cylinder. If the bearing eye is, e.g., that of a shock absorber, whose bearing eye is received between two bearing flanges of a motor vehicle axle, the depth of screwing in is to be set corresponding to the external dimensions of the bearing flanges receiving the bearing eye. However, an absolute limitation of the depth of screwing in is not absolutely necessary, because the larger dimensions of the two bearing flanges compared with the bearing eye located in between can also be taken into account by the guide cylinder and/or the mounting cylinder being screwed correspondingly less far into the corresponding support wall, without having to limit the depth of screwing in to this smaller amount.
By use of a hardened design of the stud, it is reliably prevented from being deformed even at the highest pressing forces, so that the stud is definitely unable to become jammed in the guide hole of the guide cylinder.
The stud may have a pressure piston, which is guided in a guide hole of the guide cylinder. The diameter of this guide hole is adapted to the diameter of the tightening screw. It is achieved as a result that the tightening screw or fastening screw is completely received in the guide hole with its threaded section projecting from the mounting hole of the bearing eye or of the bearing flanges at the beginning of the pressing operation. Accurate guiding and stabilization of this threaded section of the tightening screw or fastening screw is thus reliably guaranteed, so that this threaded section cannot undergo deformation even under the highest pressing forces and the tightening screw or fastening screw is reliably loosened in the mounting holes of the bearing eye.
The lateral support walls may be rigidly connected to one another via a rear wall. In addition to these lateral support walls, an upper support wall and a lower support wall, both of which extend approximately at right angles to the rear wall and at right angles to the lateral support walls, may be provided. Due to this design, the support body thus forms a kind of housing, which is open on one side and can be attached to the bearing seat in the area of the tightening screw or fastening screw. Furthermore, the upper or lower support wall may be provided as desired with a pressing-out opening for pressing out the pivot pin. The respective other of the upper or lower support walls has, by contrast, an approximately U-shaped opening. In the state attached to the bearing eye, this opening surrounds the pivot pin to be pressed out at least partly. At the same time, the support wall with the U-shaped opening is used for support on the bearing eye during the pressing out of the pivot pin and it correspondingly also absorbs the pressing forces. This pressing-out device thus acts essentially at right angles to the pressing device, which is intended for pressing out the tightening screw or fastening screw. An extremely dimensionally stable support body is obtained, which is designed such that, on the one hand, the tightening screw or fastening screw can be removed in a simple manner and, on the other hand, the pivot pin can be pressed out of its bearing bore in a very simple manner.
The pressing-out device for pressing out the pivot pin may be formed by a pressure screw, which is screwed through a corresponding threaded hole of the support wall as well as through the bearing bore of the pivot pin during the pressing out of a pivot pin. The length of this pressure screw is correspondingly also selected to be such that the pivot pin can be pressed completely through its bearing bore and can thus be reliably removed from the bearing bore.
The threaded hole for the pressure screw may be part of a spacer sleeve, which is tightly fastened, directed toward the outside, to one of the corresponding support walls. In the state in which the support body is attached to the bearing eye, this spacer sleeve extends coaxially to the bearing bore of the pivot pin to be pressed out.
If such a spacer sleeve is used, the threaded hole of this spacer sleeve is provided with a radially expanding, threadless guide section toward the support wall. At the same time, the pressure screw has a pressing section, which can be pressed essentially fittingly through the bearing bore of the bearing eye. Due to this design of the spacer sleeve together with the pressure screw with its threadless section, it is ensured that the thread of the pressure screw cannot be damaged during the pressing out of the pivot pin. The service life of the device according to the present invention is substantially prolonged as a result.
If two or more pivot pins are provided in a bearing eye, a plurality of pressing-out devices may be provided corresponding to the number of pivot pins to be pressed out. In the case of such a design, the distance between the two lateral support walls is increased corresponding to the clamping flanges, so that the support body can be attached to this bearing eye in a simple manner. After the removal of a tightening screw in the bearing eye, which tightening screw is provided for bracing together for both pivot pins, each pivot pin can be pressed out in one clamping due to the multiple arrangement of the pressing-out devices. The handling is thus simplified and the operations are expedited considerably.
Mutually interchangeable pressing devices of different designs may be provided, which can be interchanged with one another as needed. This design is advantageous, e.g., when an extremely long tightening screw or fastening screw must be pressed out. In this case, this tightening screw or fastening screw can first be loosened, e.g., with a pressing device. Once the tightening screw or fastening screw has been loosened, a pressing device of a simpler design, which comprises, e.g., a simple pressing screw of greater length, can be used for the further, complete pressing out of the tightening screw or fastening screw over the remaining, relatively long path from its bearing bore. This offers the advantage that the pressing device does not have to be made needlessly large for applying extremely strong pressing forces in order to achieve the extremely long pressing path.
As an alternative to the use of a second pressing device, it is also possible to provide a plurality of studs of various lengths, which can be inserted into the pressing device one after another as the pressing path increases in order to press the tightening screw or fastening screw completely out of its bearing bore. This means that a stud of a shorter length is first used to loosen the tightening screw or fastening screw. Once the tightening screw or fastening screw has been loosened and pressed through the bearing bore by a certain amount by this stud of shorter length, a second stud is inserted, which is longer, e.g., by this pressing path. The tightening screw or fastening screw can now be pressed out of the bearing bore by an additional amount by this second stud. If this pressing path is not yet sufficient, either, another pressing bolt may be provided, which is again longer by the pressing path that can be reached with the second pressing bolt. Complete pressing out of the tightening screw or fastening screw can thus be achieved by using a plurality of pressing bolts of different, mutually coordinated lengths. It is advantageous in this connection that an impact screwdriver can be used to actuate the pressing device for the complete pressing path because of the extremely stable design of the pressing device, so that a shorter working time can be achieved even if the stud must be replaced several times.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.